In the visual sciences it is known that the [oblique effect][1] can be reduced by means of training. The oblique effect is observed when testing subjects psychophysically with a grating acuity task (*e.g.*, the [BaGa test][2]). [Visual acuity][3] is better when horizontal or vertical gratings are tested than when diagonals are used. The performance in discerning diagonal gratings has been shown to improve after training subjects, although performance in the cardinal directions stays better than the oblique stimuli. 

The [oblique effect has been observed in the tactile sense][4] too. However, the amount of papers in the scientific literature is quite restricted in the tactile modality. I wasn't able to find evidence in the literature whether training can improve people's performance in tactile diagonal grating tasks. 

**Does training improve people's performance in oblique tactile gratings relative to gratings with horizontal/vertical orientations?**    

  [1]: https://en.wikipedia.org/wiki/Oblique_effect
  [2]: http://iovs.arvojournals.org/article.aspx?articleid=2126684
  [3]: http://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/visual-acuity?sso=y
  [4]: https://www.ncbi.nlm.nih.gov/pubmed/1483524